To perform an optimum magnetic recording on the tape drive apparatus, an accurate geometric relationship must be maintained between the path of the magnetic recording tape and the write-read gaps of the magnetic recording head. This geometric relationship is referred to as the “head alignment”. The head alignment includes the head-to-tape relationship in three main orientations. The “azimuth” relates to the perpendicularity of the head-gap with respect to the path of the tape. The “zenith” relates to the tilt of the head with respect to the tape. The “penetration” refers to the amount of penetration of the magnetic head into the path of the tape. This head penetration controls the wrap angle of the tape with respect to the contour of the magnetic recording head.
Due to the normal manufacturing tolerances of the components of the tape path and the head positioner of the tape drive head positioning apparatus, the location of the head-gap varies with respect to the tape path. In light of this, after assembly of the tape drive, it is very unlikely that the head will be precisely aligned to the tape path within the necessary alignment tolerances. Additionally, tape cartridges are often interchanged between drives. This requires that the data recorded on one cartridge on a tape drive must be able to be read by the same family of other tape drives. Hence, each of the tape drives needs to have its head properly aligned to provide consistency between the tape drives.
Normally, after the assembly of the head, positioner and the tape path components, it is common practice to set the head-alignment within the required limits. This alignment is set at the factory and is considered one of the most critical procedures in the assembly of the tape drive. However, although this should be considered a final step of the procedure, conventional practices have often required additional steps to lock the alignment into place. A concern with this is that the locking operation itself often causes the alignment to change and require repetition of the alignment setting operation.
Another problem present in conventional systems is the potential migration of the head or the head positioning system when the tape drive is subjected to a reasonable shock or vibration. When this occurs, the head alignment changes and affects the write-read performance of the tape drive. Conventional systems strictly rely on fasteners to keep the alignment in place and do not provide adequate protection to secure the alignments against a shock-vibration environment.
The increasing capacity of tape drives requires increasing accuracy of the alignment system. In order to achieve this increasing accuracy, the alignment offset must be measured precisely and then corrected using a predictable mechanism. The correction of the measured error to within a required accuracy requires a fine-resolution in the alignment system. Conventional systems use cams, for example, to set such alignments, but do not provide for the calibration of the cam rotation to correct certain skew amounts nor provide a mechanism for rotating these cams.
Another concern with the head alignment systems is the difficulty in re-setting alignments in conventional tape drives without incurring either a large amount of disassembly or without damaging the tape drive. For instance, certain conventional tape drives employ applying a permanent adhesive to bond a head placing mechanism in place. If for any reason the alignment is not within the required specifications, the bond joint must be broken and in turn, the head may get damaged. In addition, application of the bonding agent near the head element is not a preferred procedure, as the adhesive may get deposited on the head surface and result in deterioration of write-read processes.
Another concern related to the head-aligning process is the potential affecting of the performance of some of the critical components of the tape drive. Certain conventional alignment processes will affect the performance of certain critical components of the tape drive. This can result in the reduction in the life of these components or hinder the performance of the system.